If she had been given time to think about it, she probably would have thought that Captain Christopher would be most uncomfortable around Madeline, who must resemble a tree to his eyes, or maybe even Spock, who looked very human right up until he didn't. If she'd been given a chance to refresh her 20th century Earth history, she might have thought that Chekov's accent and enthusiasm for all things Russian (real or imagined) would have unsettled him. But it's her form his eyes keep flicking nervously over, like he can't quite figure out what she's doing there, her eyes he can't quite make himself meet.
It hits her as she's decrypting the radio chatter, exactly why he's so unsettled, and it feels like a punch in the gut. Something must show on her face, because he comes over to her, looking... not concerned. Something else.
"Are you doing okay?" He asks, and it becomes clear that patronization is at least part of that else.
"I'm fine," she says, leaving to room for argument.
"I can't help but notice that most of the other people in red uniforms have come and gone," he starts.
"Everyone else you've seen in a red uniform isn't a senior officer," she replies.
He blinks, looking shocked for a moment before covering it up, and she feels a bit vindicated. "What are you in charge of?" He asks.
"Communications," she answers shortly.
"You're the...radio operator?" Now that she knows what she's dealing with, she can hear what she's really being asked: How did a black girl end up running anything?
"I'm not familiar with the term," she replies, slowly. "But if a radio operator is the person who coordinates repairs of the ship, and the movements of the fleet whenever the Enterprise is in a battle situation, monitors all frequencies when orbiting a world advanced enough to emit them, translates official documents, relays confidential orders, and ensures that the public relations and intelligence officers are doing their jobs as best as they can, then yes, that's what I am."
She smiles. Christopher's mouth forms a small, round 'o'. He looks like he's going to comment, but Uhura picks up an increase in chatter on the air force base's security channel- it looks like Kirk and Sulu are in trouble. She turns away from him and back to her work, signaling Spock as she does.
She has more important things to do than worry about someone who hasn't stopped to think that the future could be more than space travel and aliens.